ReRAM (Resistance Random Access Memory, resistance change memory) has been paid attention as an indefinitely rewritable memory having an integration density comparable to that of DRAM and high-speed performance comparable to that of SRAM.
The above-mentioned ReRAM comprises a resistance change element including a laminate film that has a high melting-point metal film (electrode film) and a metal oxide film (resistance change film) changing its resistance reversibly in response to application of a voltage. Ion milling has often been used for etching processing of such a high melting-point metal film and a metal oxide film. Since ion milling is physical sputter etching, it has been however difficult for ion milling to ensure the selectivity with respect to various materials used for a mask, and thus problems such as film deposition on a sidewall have been occurred. Hence, in particular, ion milling is not suitable for manufacturing a large capacity resistance change memory requiring a microfabrication technology, and thus yield has not been improved so far.
Technologies developed in semiconductor industries have begun to replace such an ion milling technology. Among them, an RIE (Reactive Ion Etching) technology capable of ensuring uniformity for a large area substrate with a diameter of 300 mm and having an excellent microfabrication property has been expected.
RIE using a chlorine based gas has been utilized for etching of a high melting-point metal film and a metal oxide film. For the RIE using a chlorine based gas, because reactivity at room temperature is generally poor, it is difficult to process them without an etching residue and deposition on a sidewall, and thereby it is necessary to heat a substrate to a temperature of 250° C. or more so as to improve reactivity. The substrate temperature however cannot be made high because device damage will occur in the resistance change element at a high temperature, resulting in difficulty for RIE to obtain a good etched shape. Furthermore, it has been necessary for the conventional RIE to carry out corrosion processing after etching processing (refer to Patent Document 1).
Patent Document 1: Japanese Patent Application Laid-open No. 2003-282844